We have a section called Tropical Fish Profiles, second tab from the left in the blue bar at the top, and many fish are now included. You will find information on neon tetra and guppy. You can also click on the shaded fish name in posts to see that fish's profile.

The eel is the fish that would likely not go with any of the other fish (or the frog). You will need to know the species to find further information.